Rolling contact



March 27, 1962 P. M. GALLAT|N 3,027,436

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VTT f Z6/ 3 56@ i? A9' @A ez ez gmmm \f; 56 SDMXWSMM /fmmmm United States Patent @hice 3,827,436 Patented Mar. 27, 1962 3,027,436 ROLLING CONTACT Paul M. Gallatin, Breoklield, Wis., assigner to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed Aug. 20, 1958, Ser. No. 756,125

8 Claims. (Cl. 200--87) This invention relates generally to electrical contactors and in particular to that type of contacter which formerly required a large flexible lead to carry the current from a terminal to the movable contact.

The llexible lead which exists in heavy duty contactors is often a source of trouble because of the large size required to carry the rated current of the contacter. In previous high current contactors an appreciable portion Iof the armature magnet force is consumed in moving the flexible lead. This meant that the magnet had to be substantially larger than the size required to move the contacts alone. Since the problem of contact bounce is related to the mass ofthe moving elements, the use of a large diameter flexible lead tends to aggravate this problem also.

Priorrart devices attempted to overcome some of the disadvantages of the large leads by attaching the lead to the movable contact element at the pivot point of the element. This is effective in reducing contact bounce because it minimizes the elect of the increased mass, however, this configuration does not oier any assistance in reducing the size of a contacter. Furthermore, there is still the twisting movement of the contact lead which must be overcome by the actuating magnet. Since the flexible lead is fasytened at right angles to the plane of movement of the movable contact, the width of the contacter must be substantially increased to accommodate this lead.

Still another problem inherent in a contacter using such flexible leads is the diiculty experienced with fraying. The continual flexing, even about a substantial radius, leads to deterioration and breakage of the wires in the llexible lead and the resulting increased resistance may cause overheating or failure of a contacter.

My invention eliminates the requirement of a exible lead by the use of a rolling contact which is held in constant engagement with the terminal to which the contacter is to be connected. The movable element then becomes somewhat of a bridging contact with one end of the bridging contact held in continual rolling engagement to eliminate any arcing at this point.

My new structure has the advantage of reducing the size of the actuating magnet'by elimination of the force required to move the liexible lead. The contacter embedying my invention will have a reduced size since there is no need for the clearance formerly required by a ilexible lead entering at the point of pivotal suspension of the movable contact.

It is an object of my invention to provide a heavy duty contacter which does not require the incorporation of a flexible lead to carry the current from a terminal to the movable contact.

It is another object of my invention to provide a contacter which has a reduced width and a smaller actuating magnet.

It is still another object of my invention to provide an improved contacter with greatly improved life and reduced s1ze.

VOther objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth by way of illustration and example certain embodiments of this invention.

In the drawings,

FIG. 1 is a side elevation with parts broken away of a contacter embodying my invention;

FIG. 2 is a front elevation of the contacter shown in FIG. l; and

FIG. 3 is an enlarged section taken along the line'III- Ill in FIG. 1.

In FIG. l, a terminal 1 is connected to a bus bar 2 by means of belts 3. The bus bar 2 leads to the circuit to be controlled by the contacter. Terminal 1 leads to a blowout coil 6 which is wound about a core 7 of magnetic material. The other end of blowout coil 6 leads to a fixed contact element 8 having a contact surface 11 and an arc horn 12. The contact surface 11 is held in position on contact element 8 by screw 9. A current llowing through the blowout coil 6 induces a magnetic llux in the core 7 which travels through the blowout shoes 13 to produce a magnetic field in the space between the blowout shoes.

The magnetic field so produced propels the arc formed on separation of the contacts 8 and 16 into the arc box 17 where it is cooled and distended to be quickly extinguished. The arc box 17 is made of an insulating material and is mounted by means of a pin 18 which tits into a notch 21 in the blowout shoe 13 and a spring clip 22 which engages a bracket 23 mounted on the contactor frame 26.

The lixed contact element 8 makes Contact with the movable contact element 16 which has a contact surface 27 and an arc horn 28. The contact surface 27 is held in position on contact element 16 by screw 29. The movable element 16 is fastened to the electromagnetic actuating means 31, consisting of a solenoid 32, movable core 33, by means of coupling 36.

The coupling 36 may be of any suitable type in which the movable contact element 16 is allowed to pivot at the point of engagement. Connection to the solenoid 32 is made through terminals 37 and 38 shown in FIG. 2. When the solenoid is energized through terminals 37 and 38, the core is attracted upward against the force of spring 39 until the contact surfaces 11 and 27 are in engagement. When the solenoid is deenergized the movable contact surface 27 is removed from engagement with the contact surface 11 by the action of spring 39. In the embodiment shown, a restraining spring 41 holds the movable contact element 16 in position against a pair of pins 42 which ride on the shoulders 43 of clip 46.

The pin 42 and shoulder 43'combinatien allows the movable core 33 of the solenoid 32 to move up and down without binding against the sides. It is important that the pivotal motion be given to the movable contact element without imparting any transverse component of force which would cause the rolling contacts 47 and 48 to slide against each other.

Contact 48 is secured to the movable contact element 16 and contact 47 is secured to the fixed terminal 52. A bus bar 51 is connected to the terminal 52 by means of bolts 53. The bus bar 51 and bus bar 2 lead to thecircuit which the contacter is to control.

The contact 47 and contact 48 are held in engagement by the spring 56 which engages an insulating spacer 57 at one end and the movable contact element 16 at the other end. A spring retainer 58 tits inside the end of the bias spring which is closest to the movable contact member 16.

, from contaminants.

3 The relationship of the contacts 47 and 48 is better understood with reference also to FIG. 3. The pins 61 are afiixed to the terminal 52 and fit loosely into locating f holes 62 in the movable contact element 16. The spring retainer 58 has a round head 563 and a locating pin 64 which rides against thebottom of the hole in element 15 and servesto keep the direction of the biasing force along a radius of the contact surface 48 drawn to the point on contact surface 4S where it engages the contact surface 47.

With reference again to FIG. 1, the contact surface 48Y is shown with a convex face and contact 47 with a flat surface. Y While this is the preferred embodiment, the essential function is a rolling action between these faces without any slipping or sliding and other configurations which produce this result would also be satisfactory. For example, the contact surface 47 could be convex and the surface 48 flat or both surfaces could be convex. Also surface 47 could be concave with radius of curvature greater than radius of convex contact surface 48. y It has been found that the contacter operates satisfactorily with the bias spring 56 in the location shown. It would be possible to relocate this spring, for example, to the right 'of its present location, and eliminate the necessity for spring 39. An important feature of this invention is the novel manner in which the contacts 47 and 48 are protected v It is well known that a rolling contact is the most susceptible to improper operation due to dirt lodging on the Contact surface. These contacts must be well protected to prevent such an occurrence. an elastic material, such as rubber, which is compressed Vbetween terminal S2 and the movable contact element 16, an effective seal is formed which prevents contamination of the contacts.

Although but one embodiment has been shown and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What is claimed is: 1. In an electric switch having a movable contact elenient, a first terminal, means connecting said first terminal to said movable contact element comprising, a contact surface on said terminal, a contact surface on said movable contact element, one of said contact surfaces having a convex face adapted to roll upon the other of said surfaces, means providing a biasing force directed along a radius of said convex face surface to the point of contact between said surfaces to hold said contact surfaces in rolling engagement during operation of said movable contact element.

2. In an electric switch having movable contact elements, a first terminal, means connecting said first terminal to said movable contact element comprising, a contact surface on said terminal, a contact'surface on said movable contact element, one of said contact surfaces having a convex face adapted to roll upon the other of said surfaces, said other surface having a substantially fiat face to prevent sliding of said convex surface relative to said fiat surface, bias means holding said contact surfaces in rolling engagement during operation of said movable contact element.

3. In an electric switch having a movable contact element, a first terminal, means connecting said first terminal to said movable contact element comprising, a contact surface on said terminal, acontact surface on said movable contact element, one of said contact surfaces having a convex face perpendicular to the direction of Vmovement of said movable contact element and adapted to roll Aupon the'othe'r of said surfaces, said other surface having a substantially fiat face to prevent sliding of said convex surface relative to said flat surface, bias means holding By enclosingthe contacts with a washer 65 of said contact surface in rolling engagement during operation of said movable contact element.

4. in anelectric switch having a movable contact element, a first terminal, means connecting said first terminal to said movable contact element comprising, a contact surface on said terminal, a contact surface on said movable contact element, said contact surfaces each having a convex face perpendicular to the direction of movement of said movable contact element and adapted to roll against the other, bias means holding said contact surfaces in rolling engagement during operation of said movable contact element.

5. In an electric switch, a fixed contact element, a first terminal connected to said first contact element, a movable contact element adapted to engage said fixed contact element, electromagnetic operating means, means connecting said operating means to said movable contact element whereby said operating means brings said movable contact element into engagement with said fixed contact, a second terminal, means connecting said second terminal in said movable contact element comprising, contact surface on said movable contact element, a contact surface on said second terminal, one of said contact surfaces having a convex face adapted to roll upon the other of said surfaces, means providing a biasing force directed along a radius of said convex face surface to the point of contact between said surfaces to hold said contact surfaces in rolling engagement during operation of said movable Contact element.

6. In an electric switch, a fixed contact element, a first terminal connected to said first contact element, a movable Contact element adapted to engage said fixed contact element, electromagnetic operating means, means connecting said operating means to said movable contact element whereby said operating means brings said movable contact element into engagement with said fixed contact, a second terminal, means connecting said secholding said contact surfaces in rolling engagement during operation of said movable contact element.

7. In an electric switch, a fixed contact element, a first terminal connected to said first contact element, a movable contact element adapted to engage said `fixed contact element, electromagnetic operating means, Vmeans connecting said operating means to said movable contact element'whereby said operating means brings said movable contact element into engagement with said fixed contact, a second terminal, means connecting said second terminal and said movable contact comprising, a contact surface on said movable contact element, a contact surface on said second terminal, one of said contact surfaces having a convex face perpendicular to the direction of movement of said movable Contact element and adapted to roll upon the other of said surfaces, bias means holding said contact surfaces in rollingengagement during operation of said movable contact element.

8. In an electric switch, a fixed contact element, a first terminal connected to said first contact element, a movable contact element adapted to engage said fixed contact element, electromagnetic operating means, means connecting saidoperating means to said movable contact element whereby said operating means brings said movable contact element into engagement with said fixed contact, a second terminal, means connecting said second terminal and Vsaid movable contact comprising, a contact surface on said movable contact element, a contact surface on said second terminal, one of said contact surfaces having a convex face perpendicular to the line of movement of said movable contact element and adapted to roll upon the other of said surfaces, said other surface having a convex face, bias means holding said contact surfaces in rolling engagement during operation of said movable contact elements, alignment means on said terminal and said movable contact element for restricting the movement of said movable contact element.

References Cited in the le of this patent UNITED STATES PATENTS 1,222,714 Baehr Apr. 17, 1917 6 Armstrong May 16, 1933 Ellis et al Nov. 12, 1935 Weiser Apr. 25, 1944 Ebert Aug. 24, 1944 Schwager et al. Sept. 26, 1944 Derungs Sept. 10, 1946 Netzel Feb. 3, 1953 

